Towards sustainable water use in intensive and super-intensive olive orchards of Alentejo across multiple scenarios for present and future climate

Orchards present challenges for water management due to their anisotropic and heterogeneous canopy geometries. Over the past decade, the expansion of intensive and super-intensive olive orchards worldwide, and particularly in the Alentejo region, southern Portugal, has underscored the need for clear guidelines to accurately estimate crop water requirements for profitable yield, water saving, and environmental adequateness of these complex systems. To address these issues, multiple scenarios were developed based on the characteristics of a typical irrigation district in the region, incorporating relevant factors such as crop density, soil type, climate demand, and water saving irrigation (WSI) strategies. The Allen and Pereira (2009) approach was used for computing the actual basal crop coefficient (K cb ) based on observations of the fraction of ground cover by vegetation (f c ), plant height (h), and degree of stomatal adjustment (F r ). The SIMDualKc water balance model was then used to compute all terms of the daily soil water balance, i.e., actual crop evapotranspiration, percolation, and runoff. The results demonstrate how K cb values respond to these various factors and highlight the significant water savings achievable through WSI strategies. Climate change projections for the region, where temperatures and rainfall were generated using eight different global circulation models, predict future increasing imbalances between water availability and demand. Considering present and future scenarios, these findings contribute to the development of effective coping strategies that contribute to the sustainability of intensive and super-intensive olive production systems. • Guidelines for irrigation of super intensive and intensive olive orchards were proposed. • The Allen and Pereira (2009) approach and the SIMDualKc model were used for tailored assessment of crop irrigation needs. • Factors such as crop density, soil type, climate demand, and water saving irrigation (WSI) strategies were considered. • Variations in K cb act were dependent on orchard characteristics while K c act variability was dictated by the soil water. • Improved WSI strategies and farmers training are required to cope with climate change.